A) Quantification Basis
1. Is reported quantity based on absolute calibration against a reference standard, or relative/normalized signal?
Reported quantities are derived from calibration against an external reference standard.
2. Do you average replicate injections or preparations before reporting a single value?
Replicate injections are performed only for the reference standard to verify instrument performance; daily system suitability typically demonstrates an RSD of < 0.3%.
B) Sample Preparation
3. Do you assume full recovery of peptide upon reconstitution, or do you measure recovery implicitly?
Complete recovery upon reconstitution is assumed, and no correction is applied to the measured quantity.
4. Do you correct for adsorption, losses, or degradation, or are these reflected in the final number?
No explicit corrections are applied for adsorption, material loss, or degradation, as reference standards and samples undergo the same preparative workflow.
C) Detection & Calculation
5. Which detector(s) are used for quantification (UV, MS, both), and which signal is authoritative for quantity?
UV detection is used for quantitative determination of all peptides; mass spectrometry is employed only for characterization or when compounds lack chromophores.
6. How is purity incorporated into quantity (e.g., normalization vs independent measurement)?
Purity and quantity are determined independently; purity is not used to adjust the reported quantity.
D) Precision & Uncertainty
7. What is your stated margin of error for this peptide, and does it include preparation + calibration uncertainty?
The typical overall margin of error for most peptides is estimated to be 2–5%, encompassing method and preparation variability.
8. Are reported values rounded, truncated, or raw calculated outputs?
Quantity values are rounded to four significant figures. Chromatographic purity values are reported as raw outputs from the data analysis software without additional rounding.
E) Interpretation
9. Does your reported “mg per vial” represent recovered mass, inferred mass, or label-equivalent mass?
Reported quantities represent the recovered mass of material and are not adjusted.
10. Under what conditions would you expect two vials from the same batch to differ by <1%?
The primary contributor to vial-to-vial variability within a batch is the precision of the manufacturer’s vial-filling equipment.